The head of household filing status is a special status the Internal Revenue Service reserves for unmarried taxpayers who care for qualifying children or dependents. This status does not necessarily apply to just one member of a household, but rather to any adult in a household who meets IRS criteria to file with the status. You and your partner may each qualify to file as head of household if certain conditions are met.
The IRS considers couples who have not been legally married as single taxpayers, absent of state laws. If you live in a state where you and your partner are considered married by common law, neither of you is allowed to file as head of household. If your state doesn’t consider you married, both of you can file as head of household if you meet all IRS eligibility tests for the filing status.
You and your partner can each claim head of household if you both have your own qualifying children. You must pay more than half the living expenses for the children and the children must live with you the majority of the year to qualify. Both you and your partner must meet this test individually.
If each of you pays more than half the cost of keeping up a home for your own children, you both qualify to file as head of household. The IRS rules for keeping up a home are divided amongst the parents of the children, so it doesn’t matter if you and your current partner don’t equally split your joint household bills, as long as you aren’t both the biological parents of the children you're separately claiming. In most cases, if your children live with you the majority of the year, you pay more than half the cost of providing a home to them.
If you and your partner both pass all the IRS tests to claim head of household, you must file separate returns and claim your own qualifying children. It doesn’t matter if the same address is used on your returns because you’ll each qualify for the status individually.